Charts not created correctly when worksheet should be quoted
*Created originally on Bitbucket by [jpaduart (Johan Paduart)](https://bitbucket.org/%7Bb01ebd5d-4d77-4709-abff-cc2df7f0be34%7D/)* When running the code below, the chart reference to the worksheet with a "%" in the sheet name, does not appear. Similar to https://bitbucket.org/openpyxl/openpyxl/issues/788 (sheet reference should be quoted) ``` #!python import openpyxl from openpyxl.chart import LineChart, Reference, Series wb = openpyxl.Workbook() ws1 = wb.create_sheet("SheetWith%", 0) ws2 = wb.create_sheet("SheetWithout", 0) ws3 = wb.create_sheet("Graph") lc = LineChart() data = Reference(ws1, min_col = 1, min_row = 24, max_col = 1, max_row = 64) series = Series(data, title = "With%") lc.append(series) data = Reference(ws2, min_col = 1, min_row = 24, max_col = 1, max_row = 64) series = Series(data, title = "Without%") lc.append(series) ws3.add_chart(lc, "A1") wb.save('test.xlsx') ```
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