The 1986-87 Broadway theater season, buoyed by three big British musicals, reversed a five-year slide in attendance, box-office receipts and number of productions, the League of American Theaters and Producers announced Tuesday. End of season statistics: 41 productions--15 new plays, 9 new musicals, 10 revivals and 7 special attractions such as Jackie Mason's successful one man-show, "The World According to Me." There were 33 new productions in each of the two previous seasons, and 36 in 1983-84. Broadway attendance: 7.05 million during the 1986-87 season, up from 6.56 million the previous year, and box-office gross climbed to $209 million from $191 million during the 1985-86 season. Touring companies of Broadway shows had a leaner year, playing 901 weeks on the road last season compared to 983 in 1985-86. Box-office take on the road totaled $223 million, a 5% dip from the previous season's $235 million.