Bob: 0 /10
Bob: 1 /10
Jane: 9 /10
Drake: 5 /10
Dan: 4 /10
Josh: 1 /10
Dan: 5 /10

dataList = []
with open(sourceFile,'r') as dataFile:
    for line in dataFile:
        dataList.append (line.split(":"))
dataList.sort(key = lambda x : x[1],reverse = True)
final = [":".join(line) for line in dataList]
with open (newFile,'w') as finalFile:
    for line in final:
        finalFile.write(line)