0. Yes. 0.
I own a couple moisture wicking active tops by adidas, nike, etc. But I don't own a jersey. I bike mostly in capris or rolled up pants/jeans & chrome shoes to work and a t-shirt with my messenger bag slung across my back. If it is really hot - I wear a moisture wick top and carry and extra shirt in my bag. Maybe a jersey someday.
"Things look different from the seat of a bike carrying a sleeping bag with a cold beer tucked inside." ~Jim Malusa
2009 Trek 520-Brooks B-17 Special in Antique Brown
2010 Surly Long Haul Trucker-Brooks B-17 Standard in Black
1983 Fuji Espree Single Speed-Brooks B17 British Racing Green