Draw Google Line Chart with multiple missing values

平成３０年１月１４日（日曜日）

data.addRows([
[1, 37.8, 55.0],
[2, null, 69.5],
[3, null, 57],
[4, null, 18.8],
[5, null, 17.6],
[6, null, 13.6],
……

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