Sum based on Element attribute in XSLT transformation

I am new to XSLT and facing a problem in transformation of XML. I need to transform an output in text file as with ',' seperated.

Need Help to do the total based on type Descriptor.

Output should lokk like:

Co code, ID,   type, amount
DEEP1,  12345, phone, 14
DEEP1,  12345, food,  8
DEEP1,  12346, phone, 16

XML:

<Root>
<Employees>
<Employee>
<Co_Code>DEEP1</Co_Code>
<ID>12345</ID>
</Employee>
<Type Descriptor="Phone"></Type>
<amount>8</amount>
</Employees>
<Employees>
<Employee>
<Co_Code>DEEP1</Co_Code>
<ID>12345</ID>
</Employee>
<Type Descriptor="Phone"></Type>
<amount>6</amount>
</Employees>
<Employees>
<Employee>
<Co_Code>DEEP1</Co_Code>
<ID>12345</ID>
</Employee>
<Type Descriptor="Food"></Type>
<amount>8</amount>
</Employees>
<Employees>
<Employee>
<Co_Code>DEEP1</Co_Code>
<ID>12346</ID>
</Employee>
<Type Descriptor="Phone"></Type>
<amount>8</amount>
</Employees>
<Employee>
<Co_Code>DEEP1</Co_Code>
<ID>12346</ID>
</Employee>
<Type Descriptor="Phone"></Type>
<amount>8</amount>
</Employees>
</Root>

Thanks a ton in Advance.Any useful link or snipeet code will be much appreciated ,Please let me know if need more information.