It's probably on the order of 5 decades. OTOT, I never sang the "Star Spangled Banner" in high school, even though I went to every home football game ...
... it's hard to sing and play the flute at the same time. The most recent time I sang the "Star Spangled Banner" was, IIRC, last October, at the Belmont Water Dog Run where I did the 10K distance.