The past year in the arts has been Boffo BO, as they as in Variety. Translation big box office.

Film, dance, music, and the theater have all been resoundingly successful in Washington. Although it's still too early to tell precisely, it appears that 1977 may have been the highest grossing year yet for the arts here.

Theaters at the Kennedy Center for the Performing Arts, for instance, have been filled to more than 80 per cent of capacity on average - an astounding feat at any singly theater, let alone a three-house complex. That occupancy rate is one of the highest for any all hall in the world.

The Motion Picture Association of America estimates that domestic box-office grosses will reach an all-time high of $2.35 billion this year, up 15 per cent from last year.

Locally, Paul Roth of Roth Theaters estimates that area film business has increase 10 per cent (this at inflated ticket prices). He said 1977 was a very good year for his organization, largely because of durable first-runs at his houses, like "Rocky" and "Annie Hall."

The Circle Theater chain also reports a good year, and said it plans to open a new first-run twin theater, the Tenley Circle in February. One house will seat 520, the other 220.

It was a bad year for K-B Theaters, which has watched its earnings decline for the past three years, presumably dating from the entry of General Cinema Corp, into the area in 1975 with the Jenifer and Springfield Mall Theater. K-B passed up an opportunity to have "Star Wars" exclusively at the MacArthur, which has since been turned into a repertory house, K-B also suffered this summer with losers like "Exorcist II" and "Sorcerer," and laid off a few employees to cut its payroll.

On the music scene, attendance and income generally climbed. The National Symphony had 19,223 subscribers this year, compared with last year's 16,122, for a montary increase of $1.3 million versus last year's $910,000. The first 21 of this season's concerts were completely sold out. Expenses this year, however, are much higher, partly because of increased salaries stipulated by the musicians' last contract.

The Washington Opera this year has projected earnings of $450,000, compared with last year's $250,000.

On the popular music front, The Capital Center expects to gross about the same as last year. The Cellar Door reports that attendance is up well over last year, and the Childe Harold has done "exceptionally well," according to one of its operators.

The jazz scene in Washington also has been doing well. Two clubs - Blues Alley and the Showboat - are bringing in nationally known artists on a regular basis.

Record sales are also reported to be up, on both a national and local basis.

Dance continues to be a mixture of boom and bust. Attendance figures continued high this year, with the so-called dance explosion still evidently in effect. The Kennedy Center and Wolf Trap have done at least as well as in previous years.

A "City Dance" festival at the Warner Theater proved that local audiences will come downtown for local dance, if the programs are attractively packaged. Dance was restored to the Carter Barron last summer after a five-year hiatus and did remarkably well.

Last year, when the American Ballet Theater premiered its Baryshnikov version of "The Nutcracker," the local Washington Ballet feared that its own life-supporting version would bomb. Consequently, it cut its run by boat half. Still, the limited number of performances were sold out. This year, with the ABT "Nutcracker" back on both stage and TV - as well as the Bolshoi "Nutcracker" on network television, the Washington Ballet resumed a full 23-perfomace schedule of its own version. It sold out completely before opening night.

Broadway this year posted a $93 million gross, along with $82 million for its touring productions. The Kennedy Center production of "Pippin," which opened five years ago and returned this summer, has already grossed $21 million, of which $3.5 million has been net profit. Both Arena Stage and the National Theater report grosses at least as good as last year.