pre_text: Pro Forma Information The following unaudited pro forma information gives effect to the acquisition of AutoGuide as if the acquisition occurred on January 1, 2018 and the acquisition of MiR as if the acquisition occurred on January 1, 2017. The unaudited pro forma results are not necessarily indicative of what actually would have occurred had the acquisition been in effect for the periods presented: Pro forma results for the year ended December 31, 2019 were adjusted to exclude $1.2 million of AutoGuide acquisition related costs and $0.1 million of AutoGuide non-recurring expense related to fair value adjustment to acquisition-date inventory. Pro forma results for the year ended December 31, 2018 were adjusted to include $1.2 million of AutoGuide acquisition related costs and $0.4 million of AutoGuide non-recurring expense related to fair value adjustment to acquisition-date inventory. Pro forma results for the year ended December 31, 2018 were adjusted to exclude $2.9 million of MiR acquisition related costs and $0.4 million of MiR non-recurring expense related to fair value adjustment to acquisition-date inventory.
table: For the Year Ended
table: December 31, 2019 December 31, 2018
table: (in thousands, except per share amounts)
table: Revenues $2,303,737 $2,111,373
table: Net income $464,602 $442,082
table: Net income per common share:
table: Basic $2.73 $2.36
table: Diluted $2.59 $2.30
question: Analyse this data from a financial earnings document. What was the change in diluted net income per common share from 2018 to 2019?