Added Pareto chart example.
Added Pareto chart example.

seize-the-dave/XlsxWriter,gechong/XlsxWriter,jvrsantacruz/XlsxWriter,liukaijv/XlsxWriter,mdeemer/XlsxWriter,applicationdevm/XlsxWriter,jkyeung/XlsxWriter,jmcnamara/XlsxWriter,jmcnamara/XlsxWriter,jkyeung/XlsxWriter,jmcnamara/XlsxWriter,jvrsantacruz/XlsxWriter,Thhhza/XlsxWriter,applicationdevm/XlsxWriter,seize-the-dave/XlsxWriter,yaojingwu1992/XlsxWriter,liukaijv/XlsxWriter,gechong/XlsxWriter,applicationdevm/XlsxWriter,liukaijv/XlsxWriter,liukaijv/XlsxWriter,yaojingwu1992/XlsxWriter,jvrsantacruz/XlsxWriter,jvrsantacruz/XlsxWriter,Thhhza/XlsxWriter,mdeemer/XlsxWriter,yaojingwu1992/XlsxWriter,mdeemer/XlsxWriter,gechong/XlsxWriter,jkyeung/XlsxWriter,seize-the-dave/XlsxWriter,yaojingwu1992/XlsxWriter,Thhhza/XlsxWriter,jmcnamara/XlsxWriter,gechong/XlsxWriter,applicationdevm/XlsxWriter,Thhhza/XlsxWriter,mdeemer/XlsxWriter,seize-the-dave/XlsxWriter,jkyeung/XlsxWriter