John Williams, the cinema's most widely and wildly celebrated composer, is a nominee again this year for The Book Thief (you can download some sheet music from the score here). He is 82 years old but in a delightfully senior twist, he is only the third oldest nominee (after June Squibb and Patricia Norris). IMDb's database for composers is very confusing so I can't share "number of original scores" but his feature film career, starting with Daddy-O (1958) and continuing on through the The Book Thief (2013), is prolific and highly regarded with more presumably to come since the Indiana Jones and Star Wars franchises are still alive and so is he.
His Oscar record is the closest anyone's ever come to total Academy infallibility (if you discount the people who only made one or two pictures). In the past 46 years, starting with the adaptation of the music in The Valley of Dolls (1967) and ending with his original compositions for The Book Thief (2013) he has been nominated 49 times, winning 5 Oscars.
I don't know what kind of a percentage that is -- again, the films are hard to count and some won't have been eligible since he does a lot of franchises (and those are sometimes disqualified for lack of enough new material) but I'd wager that his record is something certifiably insane like 90% of his original compositions being named one of the year's five "Best".
In other words, if he scores it, they're nominating it. Period.
Strangely, given their crazy-cuckoo devotion, he has only won the statue twice in the past 30 years. His most recent statues were for Schindler's List (1993), E.T. (1982), with his heyday being in the seventies when he won thrice for Star Wars (1977), Jaws (1975) and Fiddler on the Roof (1972... in the Adaptation category which they no longer have).
Do you think he'll win a sixth Oscar or an honorary* soon?
*in the unique star-subservient logic of the Academy, performers who've already been amply rewarded with gold are sometimes given an extra rather than honoring someone without trophies. See the recent baffling Honorary for 1961's Best Actress Sophia Loren's for her "memorable performances", instead of taking the opportunity to honor one of numerous classic and respected actresses who've never won and are still living.