Not much, according to this blog post, even though putting them together apparently takes four to six hours of invasive investigation into the rape victim’s body, and despite their usefulness in reaching convictions. They’re just left lying around.
It would be good to know more actual numbers and what it’s like in other countries.
Feminist Philosophers 
Anyone taking even four hours to “put together” a rape kit has been poorly and inadequately trained (if trained at all).
Aside from the impact it has on an individuals case, career rapist rape a dozens of women, some even 60 or more. Having all rape kit evidence collected properly, tested, and stored digitally would be a valuable tool for preventing a whole lot future of rapes by prosecuting the rapist for all the rapes he’s committed and getting the most pernicious and dedicated rapists off the streets.
Coffee and new glasses, please. Sheesh. Sorry for the errors.