what is the three most commonly performed specimen test in 2101?
select t1.spec_type_desc from ( select microbiologyevents.spec_type_desc, dense_rank() over ( order by count(*) desc ) as c1 from microbiologyevents where strftime('%y',microbiologyevents.charttime) = '2101' group by microbiologyevents.spec_type_desc ) as t1 where t1.c1 <= 3