What letter grade would you give New York City subways for cleanliness? An A, B, C, D, or an F?

TRACK POINTS	06/21/10	05/17/11	n/a	n/a	n/a	n/a	n/a	n/a	n/a
	± 4.1%	± 4.5%	n/a	n/a	n/a	n/a	n/a	n/a	n/a
Track All Subway ridersTrack Gender Male Track Gender Female Track Age 18-34 Track Age 35-54 Track Age 55+ Track Race White Track Race Black Track Race Hispanic Track Race Other	ALL	ALL	n/a	n/a	n/a	n/a	n/a	n/a	n/a
A	7%	2%	n/a	n/a	n/a	n/a	n/a	n/a	n/a
B	23%	22%	n/a	n/a	n/a	n/a	n/a	n/a	n/a
C	39%	33%	n/a	n/a	n/a	n/a	n/a	n/a	n/a
D	17%	20%	n/a	n/a	n/a	n/a	n/a	n/a	n/a
F	11%	21%	n/a	n/a	n/a	n/a	n/a	n/a	n/a
Not Sure	2%	2%	n/a	n/a	n/a	n/a	n/a	n/a	n/a
Total	100%	100%	n/a	n/a	n/a	n/a	n/a	n/a	n/a