Overlay: Unemployment vs Historical Events

I remember loving encyclopedias because of the transparent "overlays" which illustrate layers or parts in a picture. If you remember, human anatomy is represented "per layer" where body systems are printed per page.. and out together, shows the entire body. Lol. Fun.

Anyway, the concept of overlays came into mind when I was looking at the Philippines' unemployment graph for the past 10 years:

Source: CIA World Factbook

The Philippines' unemployment rate was slowly growing from 1998 - 2004. It suddenly peaked at 11.7% in 2004, drastically declined in 2005, and now gradually declining. Latest available data is 2010, at 7.3% of the labor force without jobs.

I was really surprised with the very noticeable rise of unemployment in 2004, then its steep decline towards 2005. This prompted me to visit the historical milestones in the country (source: Timeline of Philippine History , Wikipedia) , what was happening then?

TIMELINE

2000

Pres. Estrada declares all out war against the MILF

Pres. Estrada gets impeached by Congress

2001

EDSA II

PGMA assumes presidency 

Philippine general election 

2003 

Oakwood Mutiny 

2004

Phil general election

PGMA re-elected to 6 year term

2005 

Hello Garci scandal

2006

Coup rumors

2007

Phil general election 

Manila Peninsula Mutiniy 

2009

ICRC kidnapping

former Pres Cory Aquino dies

Ondoy 

Maguindanao Massacre 

2010 

Phil general election 

PNoy assumes presidency 

Bus hostage incident, Hong Kong 

To better get a picture of how these events are related to our graph, I "overlayed" the key events that could've possibly affected the unemployment curve.

source of graph: CIA World Factbook, click photo to enlarge

It was so interesting to plot the graph this way, where we can directly see the  indicator = event relationship. We see unemployment rising during Erap's watch, noticeably picking up when the impeachment process started. The Oakwood Mutiny was in 2003, and perhaps this caused unrest in the labor force, hence the peaking of the rate in 2004. 

There was a sharp decline in unemployment rate from 2004-2005, and has maintained its constant decline up to present time. 

Was this brought about by PGMA's election ? Perhaps people became hopeful when they knew they elected a President that will be there in the next 6 years? Or was the increase brought about by another factor, like spillover results from programs that Erap implemented during his time? 

There are many other ways to analyze this data, and this historical events approach is one of them. Perhaps one can also analyze it by comparing the unemployment rate to food productivity? Or also checking the volume of business start-ups during those times? 

What do you think, what are the other mechanisms of comparison that we can use?