query to select only Y values , if all are Y, say All

Kinldy provide me the query

select * from FILTER_User

CREATE TABLE [dbo].[FILTER_User](
	[UserName] [nvarchar](128) NULL,
	[Is_Member] [char](1) NOT NULL 
)
INSERT INTO FILTER_User (UserName, Is_Member) VALUES     ('Raj', 'Y')
INSERT INTO FILTER_User (UserName, Is_Member) VALUES     ('Ravi', 'Y')
INSERT INTO FILTER_User (UserName, Is_Member) VALUES     ('Kumar', 'Y')
INSERT INTO FILTER_User (UserName, Is_Member) VALUES     ('Gopal', 'Y')

-- If all the Values in [Is_Member] is Y, display all
select * from FILTER_User

/*
Expected Result
All
*/


INSERT INTO FILTER_User (UserName, Is_Member) VALUES     ('Sridhar', 'N')
INSERT INTO FILTER_User (UserName, Is_Member) VALUES     ('Aravind', 'Y')


-- If all the Values in [Is_Member] is not Y, display the names which are Is_Member]  Y
select * from FILTER_User

/*
Expected Result
 Raj
 Ravi
 Kumar
 Gopal
 Aravind
*/

ShanmugaRaj