How often are new elements discovered; and when was the last one discovered?

Question: How often are new elements discovered; and when was the last one discovered?
- Keywords:
  chemistry,
  discovery,
  element
Asked by to Thomas on 13 Mar 2014. This question was also asked by .
- Thomas Elias Cocolios answered on 13 Mar 2014:
  
  Element = number of protons (Z)
  For each elements, you have many Isotopes (same Z, different number of neutrons N)
  New isotopes are discovered all the time, every year. We predict that there should be ~7,000 but have only seen 3,500 so far.
  New elements are much more difficult to reach, however. There are extended studies performed in Germany (GSI), Russia (JINR) or France (GANIL). And even when a new element is discovered in a lab, it has to be reproduced in another before the IUPAP, an international body, agrees that it has been discovered and allow it to be named. Currently, IUPAP has accepted the discovery of Copernicium (Z=112) in 2009 (from its first identification in 1996), Flerovium (Z=114) in 2011 (from its first identification in 1998) and Livermorium (Z=116) in 2012 (from its first identification in 2000). Z=113,115,117,118 have been observed but remain currently unnamed. The current efforts focus on synthesising Z=119,120, for which the French team has built a new accelerator at GANIL in Caen (Normandy).

Question: How often are new elements discovered; and when was the last one discovered?