mssql buffer cache hit ratio

SELECT c1.cntr_value, c2.cntr_value, case when c2.cntr_value > 0 then c1.cntr_value * 100 / c2.cntr_value else -1 end as cache_hit_ratio_pct FROM sys.dm_os_performance_counters c1, sys.dm_os_performance_counters c2 WHERE c1.[object_name] LIKE '%Buffer Manager%' AND c1.[counter_name] = 'Buffer cache hit ratio' and c2.[object_name] LIKE '%Buffer Manager%' AND c2.[counter_name] = 'Buffer cache hit ratio base'