Do you have a link for that?
TL;DR: 1014 people claimed they were drugged and sexually assaulted. "In 21 cases (2%), a sedative or disinhibiting drug was detected..." So-called "date rape" drugs were a subset of these cases.
(Again, no judgement on those that choose to use drugs, I certainly do and I think that drug users are as deserving of protection as anyone else)
TL;DR: 1014 people claimed they were drugged and sexually assaulted. "In 21 cases (2%), a sedative or disinhibiting drug was detected..." So-called "date rape" drugs were a subset of these cases.