Find the percentage of words which starts with a vowel in a file

import java.io.*;
import java.util.*;
import java.text.*;
import java.util.regex.*;

public class FindPercentage{
    public static void main(String[] args){
        try{
        double count=0,vowel=0;
        BufferedReader br=new BufferedReader(new FileReader(new File("C:/hello.txt")));
        String ss="";
        StringBuffer buffer=new StringBuffer();
        while((ss=br.readLine())!=null){
            buffer.append(ss);
        }
        String st = buffer.toString();
        String str = st.replaceAll("[?!.]", "");
        StringTokenizer tokenizer = new StringTokenizer(str);
        String s = "";
        while(tokenizer.hasMoreTokens()) {
            s = tokenizer.nextToken().toLowerCase();
            if((s.startsWith("a")) || (s.startsWith("e"))||(s.startsWith("i")) || (s.startsWith("o"))|| (s.startsWith("u"))) {
                vowel++;
            }
            count++;
        }
        System.out.println("Total Number of words: "+count);
        System.out.println("No of words that starts with vowel: "+vowel);
        double value=vowel/count;
        double percentage=value*100;
        DecimalFormat df=new DecimalFormat("##.##");
        System.out.println("Vowel Percentage: "+df.format(percentage));
        }
        catch(Exception e){
            System.out.println(e);
        }
    }
}