Update README.md

README.md

@@ -10,7 +10,7 @@ to measure the second-forbidden, non-unique, ground-state transition
 in the beta decay of <sup>20</sup>F.
 
 The measurement was successfully completed in 2018 and the results 
-published in two papers a couple of years later:
+published in two papers a year later:
 
  * [O. S. Kirsebom et al., Phys. Rev. Lett. 123, 262701 (2019)](https://physics.aps.org/featured-article-pdf/10.1103/PhysRevLett.123.262701)
  * [O. S. Kirsebom et al., Phys. Rev. C 100, 065805 (2019)](https://journals.aps.org/prc/abstract/10.1103/PhysRevC.100.065805)