Count number of matches with different rows on multiple criteria

[teamlinerek]

I HAVE the following data:

DirectorID	CompanyID	AwardYear	DegreeType
1928993	62323	1998	Undegrad
1798822	62360	1998	Undegrad
2384193	467713	2003	Other
1769649	467713	2003	Other
1777732	1519459	2002	Undegrad
1627886	1519459	2003	Undegrad
1323941	1519459	2004	Undergrad
1839100	60212	2008	Grad
1706497	60212	2008	Undergrad

I want to count the number of unique rows (Matches) where a DirectorID matches with another DirectorID on ALL of the following criteria: (1) CompanyId, (2) within +/- one year of AwardYear, and (3) DegreeType.

The following output is what I WANT:

DirectorID	CompanyID	AwardYear	DegreeType	Matches
1928993	62323	1998	Undegrad	0
1798822	62360	1998	Undegrad	0
2384193	467713	2003	Other	1
1769649	467713	2003	Other	1
1777732	1519459	2002	Undegrad	1
1627886	1519459	2003	Undegrad	2
1323941	1519459	2004	Undergrad	1
1839100	60212	2008	Grad	0
1706497	60212	2008	Undergrad	0

What code could be used to create the "Matches" variable?

Thank you!!