There is a report here : Nyregistreringar mars 2015
Select the months via Nyregistreringar per mnad
However that still shows 98 for March. (a nice number for Sweden anyway)
122 Tesla Model S levererade i Mars!!! - Tesla Club Sweden published this morning says 122 delivered in March.
Bilsweden has a cutoff date some days before end of month, so another 24 cars were found in the official statistics direct from Trafikverket, or ELIS or PowerCircle (both behind a paywall, apparently). 38+12+122 Model S delivered in Sweden Q1-15! I make that 172.