The source explained (citation (pdf)):

In this release, the data for the energy indicator has been revised from March 2015 onwards. The revision removed the production data coming from the interconnector. Since the year 2015 is the current base period, the whole index for this indicator has been revised from the year 2000 onwards due to the change in the data for the base year. However, only the growth rates from the year 2015 onwards have been revised. Growth rates for all other periods remained the same. Moreover, since the energy index affects the total, the total production index has been revised accordingly.

In response, we have synchronized our extract (January 2000 to January 2019). Properties are otherwise unchanged.

The impacted series reside in the historical catalog (Malta » Industry » Industrial production index » 2015=100) and are:

• IPITTAM.IMLT  = Industrial production index: Total industry, (Index 2015=100, SA)
• IPIENGAM.IMLT = Energy

Because catalog locations are subject to change, the upper-right search box on DataBuffet.com provides a "find in catalog" mode that accepts a mnemonic.