DECLARE @StartDate date = 'Jan 1, 2015'

DECLARE @EndDate date = DATEADD(DAY, 30, @StartDate)

;WITH cte AS (

SELECT @StartDate AS ReportDate

UNION ALL

SELECT DATEADD(DAY, 1, ReportDate)

FROM cte

WHERE ReportDate < @EndDate

)

Select T1.[date],T1.Fail31,T2.days31,

((365*(Convert(decimal (8,1),T1.Fail31)/T2.days31))) [31Fly]

from

(

SELECT cte.ReportDate as [date],

SUM(Case when HISTORY.FAILUREDATE BETWEEN dateadd(DAY,-31,CONVERT(DATETIME, cte.ReportDate, 102))

AND CONVERT(DATETIME, cte.ReportDate, 102)Then 1 Else 0 END) As Fail31

FROM HISTORY left JOIN UNIT ON HISTORY.UNIT = UNIT.UNIT

CROSS JOIN cte

WHERE

UNIT.INSV_DATE < cte.ReportDate

AND UNIT.MODEL in('Toyota')

AND(UNIT.Customer in('Jona' ))

group by

cte.ReportDate ) T1

Inner Join

(SELECT cte.ReportDate as [date1],

COUNT(UNIT.UNIT) As Units,

sum(CASE

WHEN (datediff(dd,INSV_DATE,cte.ReportDate)) >= 31 THEN 31

WHEN (datediff(dd,INSV_DATE,cte.ReportDate)) < 0 THEN 0

ELSE (datediff(dd,INSV_DATE,cte.ReportDate))END) as days31

FROM UNIT

CROSS JOIN cte

WHERE

UNIT.INSV_DATE < cte.ReportDate

AND UNIT.MODEL in('Toyota')

AND(UNIT.Customer in('Jona' ))

group by

cte.ReportDate

) T2 on T1.[date] = t2.[date1]

Order by [date]

This query worked for me.