Please answer the given financial question based on the context.
Context: ||2019|2018|
||NO. OF RIGHTS|NO. OF RIGHTS|
|Outstanding at start of period|10,692,594|6,737,076|
|Granted during the period|4,465,617|5,691,731|
|Vested during the period|(182,601)|(586,663)|
|Lapsed during the period|(1,497,852)|(1,149,550)|
|Outstanding at end of period|13,477,758|10,692,594|
The performance rights sub-plan has also been used to compensate new hires for foregone equity, and ensure that key employees are retained to protect and deliver on the Group’s strategic direction. It has been offered to:
Executives of newly acquired businesses in order to retain intellectual property during transition periods; or
Attract new executives, generally from overseas; or
Middle management or executives deemed to be top talent who had either no or relatively small grants scheduled to vest over the ensuing two years.
Sign-on and retention rights generally do not have performance measures attached to them due to the objective of retaining key talent and vest subject to the executive remaining employed by the Group, generally for two or more years.
The performance rights sub-plan has also been used to compensate employees of the Group. Participants are required to meet a service condition and other performance measures to gain access to the performance rights.
The following table summarises movements in outstanding rights:
Question: What is the percentage increase in the number of rights 'outstanding at the start of period' from 2018 to 2019? 
Answer:
58.71